Portable RFID reading terminal with visual indication of scan trace

ABSTRACT

A portable radio-frequency identifier (RFID) reading terminal can comprise a microprocessor, a memory, an RFID reading device, and a display. The portable RFID reading terminal can be configured to display a scan trace provided by a line comprising a plurality of time varying points. Each point can be defined by a projection of a radio frequency (RF) signal coverage shape of the RFID reading device onto a chosen plane at a given moment in time.

This is a Continuation of application Ser. No. 13/359,005 filed Jan. 26,2012. The disclosure of the prior application is hereby incorporated byreference herein in its entirety.

FIELD OF THE INVENTION

The invention is generally related to encoded information reading (EIR)terminals and is specifically related to RFID reading terminalsincluding radio-frequency identification (RFID) reading devices.

BACKGROUND OF THE INVENTION

RFID methods are widely used in a number of applications, includingsmart cards, item tracking in manufacturing, inventory management inretail, etc. An RFID tag can be attached, e.g., to an inventory item. AnRFID reading terminal can be configured to read the memory of an RFIDtag attached to an inventory item.

SUMMARY OF THE INVENTION

In one embodiment, there is provided a portable radio-frequencyidentifier (RFID) reading terminal comprising a microprocessor, amemory, an RFID reading device including a radio frequency (RF) antenna,and a display. The portable RFID reading terminal can be configured todisplay a scan trace provided by a line comprising a plurality of timevarying points. Each point can be defined by a projection of thecoverage shape of an RF signal transmitted by the RFID reading deviceonto a chosen plane at a given moment in time.

In one embodiment, the portable RFID reading terminal can, by readingRFID tags attached to the items, reconcile a count of items stored in amanufacturing, retail, and/or storage facility against an expected countwhich can be received, e.g., from an external computer. In anotherembodiment, the portable RFID reading terminal can, by reading RFID tagsattached to the items, reconcile an inventory of items stored in amanufacturing, retail, and/or storage facility against an expectedinventory list received, e.g., from an external computer. In a furtheraspect, the portable RFID reading terminal can transmit to the externalcomputer the list or the count of read RFID tags.

In one embodiment, the portable RFID reading terminal can furthercomprise a two-dimensional imager. The portable RFID reading terminalcan be further configured to determine a spatial position of the RFsignal coverage shape based on a known position and orientation of theRF antenna relative to the position of the field of view of thetwo-dimensional imager.

In one embodiment, the portable RFID reading terminal can be furtherconfigured to measure a distance to an object using the two-dimensionalimager. The portable RFID reading terminal can be further configured todetermine and display the projection of the RF signal coverage shapeonto the plane defined by the physical structure which in one embodimentcan contain a plurality of inventory items.

In one embodiment, the portable RFID reading terminal can furthercomprise at least one accelerometer. The portable RFID reading terminalcan be further configured to determine a change of the spatial positionand orientation of the RF signal coverage shape based on the properacceleration values received from the accelerometer.

In one embodiment, the portable RFID reading terminal can be configuredto display a quantity of scanned items, a quantity of items which havenot be scanned yet, and/or a total quantity of items to be scanned.

In one embodiment, the portable RFID reading terminal can be configuredto display an indicator of a ratio of quantity of scanned items to atotal quantity of items to be scanned.

In one embodiment, the portable RFID reading terminal can be configuredto display a scan trace overlaid over an image of a physical structurewhich can contain one or more scanned items and/or one or more items tobe scanned. In a further aspect, the image of the physical structure canbe acquired by the two-dimensional imager or received from an externalcomputer. In one embodiment, portable RFID reading terminal can beconfigured to receive a description of the physical structure, andcreate an image of the physical structure based on the description.

In one embodiment, the portable RFID reading terminal can be configuredto display an indicator of an RF signal coverage over a scan traceoverlaid over an image of a physical structure.

In one embodiment, the portable RFID reading terminal can be configuredto display an indicator of an RF signal coverage over a current positionwithin the scan trace.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, the drawings show aspectsof one or more embodiments of the invention. However, it should beunderstood that the present invention is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 schematically illustrates a scan trace displayed by an RFIDreading terminal;

FIG. 2 schematically illustrates an RF signal coverage shape by the RFIDreading terminal;

FIG. 3 schematically illustrates a component-level diagram of oneembodiment of the RFID reading terminal;

FIG. 4 schematically illustrates a network diagram of one embodiment ofa data collection system employing RFID reading terminals;

FIGS. 5 a-5 b schematically illustrate determining a spatial position ofthe RF signal coverage shape based on the known position and orientationof an RF antenna relatively to the position of the field of view of atwo-dimensional imager;

FIGS. 6-19 schematically illustrate various methods of displaying scantraces and selected inventory quantities by the RFID reading terminal;

FIGS. 20 a-20 c schematically illustrate embodiments of an RFID readingterminal.

The drawings are not necessarily to scale, emphasis instead generallybeing placed upon illustrating the principles of the invention. In thedrawings, like numerals are used to indicate like parts throughout thevarious views.

DETAILED DESCRIPTION OF THE INVENTION

RFID reading devices usually offer improved efficiency over barcodescanning devices for retail inventory, by being capable of readingmultiple RFID tags that are within range of the RF signal transmitted byan RFID reading device. A downside to this multiple-read capability islack of scanned items localization, due to insufficient correlationbetween where the RFID reader is located or oriented, and the RFID tagsbeing read. Retail inventory management typically requires more than 90%of the RFID tags present in a department to be successfully acquiredduring the inventory process. When this high accuracy is not achieved,it is necessary to rescan the entire department, since the locations ofany unread RFID tags are unknown.

In one embodiment, there is provided a portable radio-frequencyidentifier (RFID) reading terminal configured to present a visualindication of defined areas which have been scanned and areas which havenot been scanned for RFID tags. Such a capability provides increasedoperational efficiency of RFID tag reading for retail inventorymanagement. Various embodiments of the RFID reading terminal can be usedin a numerous applications, including but not limited to, item trackingin manufacturing, storage, and retail, real-time inventory controlsystems, etc.

Item tracking and/or inventory control can be implemented by placing anRFID tag on each inventory item. The RFID reading terminal can compriseat least one RFID reading device which can be configured to read and/ormodify a memory of an RFID tag containing an encoded message. The RFIDreading device can transmit and/or receive radio frequency (RF) signalsto and from RFID tags attached to inventory items. Each RFID tag canstore the tag identifier in its memory. An RFID tag attached to aninventory item can further store in the tag's memory a product code ofthe item, an EPC (Electronic Product Code) of the item, and/or at leastone alphanumeric string identifying the item.

The RFID reading device can be further configured to output decodedmessage data corresponding to the encoded message, e.g., decoded messagedata containing identifiers of the items to which the RFID tags areattached. The RFID reading terminal can be configured to store in itsmemory and/or transmit to an external computer the item identifiersreceived from the plurality of RFID tags.

In a further aspect, the RFID reading terminal can be configured toreceive an expected count of inventory items or an expected inventorylist of items of interest stored within a storage, manufacturing, and/orretail facility. As used herein, “inventory list” shall refer to acollection of item descriptions, each item description comprising atleast the item identifier.

In one embodiment, the RFID reading terminal can receive the expectedcount of inventory items or the expected inventory list over a networkfrom an external computer. In another embodiment, the RFID readingterminal can receive the expected count of inventory items or theexpected inventory list via the user interface. In a yet anotherembodiment, the RFID reading terminal can receive the expected count ofinventory items or the expected inventory list by reading an externalmemory device connected to one of the terminal's I/O ports (e.g., a USBport, or a PCMCIA interface). In a yet another embodiment, the RFIDreading terminal can be equipped with a 2D imager and can receive theexpected count of inventory items or the expected inventory list via the2D imager, for example, by scanning a plurality of optical decodableindicia (e.g., a plurality of bar codes), or by acquiring an image of atextual document containing the expected count of inventory items or theexpected inventory list and then processing the image using opticalcharacter recognition (OCR) methods.

The RFID reading terminal can be further configured to reconcile theinventory of items stored within a storage, manufacturing, and/or retailfacility against the expected count of inventory items or the expectedinventory list by reading the RFID tags attached to the inventory items.

The RFID reading terminal can read RFID tags from a range of distancesand various terminal orientations with respect to an RFID tag beingread. To further improve the reliability of scanning operations and theterminal's operator experience, the RFID reading terminal can beconfigured to emit audible signals (e.g., beeps) to indicate anoccurrence of a pre-defined event, thus providing an audible feedback tothe operator of the RFID reading terminal. In one embodiment, the RFIDreading terminal can be configured to emit an audible signal of a firsttype every time a unique RFID tag has been successfully read andreconciled against an inventory list. The RFID reading terminal can befurther configured to and emit an audible signal of a second type everytime a unique RFID tag has been successfully read but failed toreconcile against the inventory list. The RFID reading terminal can befurther configured to emit an audible signal of a third type every timea pre-defined timeout has elapsed without reading an RFID tag. However,the audible feedback inherently fails to indicate the location of theRFID tag having been successfully read.

To further improve the readability of scanning operations, the RFIDreading terminal can in one embodiment be configured to display on theterminal's display one or more scan traces, thus providing theterminal's operator with a visual feedback with respect to the scanningprogress, as schematically shown in FIG. 1.

At any moment in time, the RF signal coverage emitted by an RFID readingterminal can be defined by a 3D shape, as schematically shown in FIG. 2.The form and size of the 3D shape defining the RF signal coverage candepend, among other factors, on the RFID transmit power level and thenumber and configuration of the RF antennas employed by the RFID readingdevice. In one embodiment, the 3D signal coverage shape can be providedby a sphere 2020. In another embodiment, the 3D signal coverage shapecan be provided by an ellipsoid. In a yet another embodiment, the 3Dsignal coverage shape can be provided by a cone.

At any given moment in time, a target scan area by an RFID readingterminal can be visualized as a projection 2040 of the 3D RF signalcoverage shape 2020 onto an arbitrarily chosen plane 2050, including animaginary plane. For a moving RFID reading terminal, a visual scan tracecan be provided by a line defined by a multitude of time varying points,each point being a projection 2040 of the 3D RF signal coverage shape2020 onto the arbitrarily chosen plane 2050 at a given moment in time.

In a further aspect, the imaginary plane onto which the visual scantrace is projected can be chosen to intersect a physical structure(e.g., a shelf) containing the inventory items, and thus the scan tracecan be overlaid over an image of the physical structure as schematicallyshown in FIG. 1.

Component-level diagram of one embodiment of the RFID reading terminalis now being described with references to FIG. 3. The RFID readingterminal 100 can comprise at least one microprocessor 310 and a memory320, both coupled to the system bus 370. The microprocessor 310 can beprovided by a general purpose microprocessor or by a specializedmicroprocessor (e.g., an ASIC). In one embodiment, RFID reading terminal100 can comprise a single microprocessor which can be referred to as acentral processing unit (CPU). In another embodiment, RFID readingterminal 100 can comprise two or more microprocessors, for example, aCPU providing some or most of the RFID reading terminal functionalityand a specialized microprocessor performing some specific functionality.A skilled artisan would appreciate the fact that other schemes ofprocessing tasks distribution among two or more microprocessors arewithin the scope of this disclosure.

RFID reading terminal 100 can further comprise a communication interface340 communicatively coupled to the system bus 370. In one embodiment,the communication interface can be provided by a wireless communicationinterface. The wireless communication interface can be configured tosupport, for example, but not limited to, the following protocols: atleast one protocol of the IEEE 802.11/802.15/802.16 protocol family, atleast one protocol of the HSPA/GSM/GPRS/EDGE protocol family, TDMAprotocol, UMTS protocol, LTE protocol, and/or at least one protocol ofthe CDMA/1xEV-DO protocol family.

RFID reading terminal 100 can further comprise a battery 356. In oneembodiment, the battery 356 can be provided by a replaceablerechargeable battery pack. The RFID reading terminal 100 can furthercomprise a GPS receiver 380. The RFID reading terminal 100 can furthercomprise at least one connector 390 configured to receive a subscriberidentity module (SIM) card.

The RFID reading terminal 100 can further comprise an imaging device330, provided, for example, by a two-dimensional imager.

The RFID reading terminal 100 can further comprise an RFID readingdevice 333. In one embodiment, the RFID reading device 333 can beconfigured to read a memory of an RFID tag containing an encoded messageand to output raw message data containing the encoded message. Inanother embodiment, the RFID reading device 333 can be configured toread a memory of an RFID tag containing an encoded message and to outputdecoded message data corresponding to the encoded message. As usedherein, “message” is intended to denote a bit sequence or a characterstring comprising alphanumeric and/or non-alphanumeric characters. Anencoded message can be used to convey information, such asidentification of the source and the model of an item, for example, inan EPC code.

In one embodiment, the RFID reading terminal 100 can further comprise agraphical user interface including a display adapter 175 and a keyboard179. In one embodiment, the RFID reading terminal 100 can furthercomprise an audio output device, e.g., a speaker 181.

It is not necessary that a device's primary function involve readingRFID tags in order to be considered an RFID reading terminal; forexample, a cellular telephone, a smart phone, a PDA, or other portablecomputing device that is capable of reading RFID tags can be referred toas an RFID reading terminal for purposes of this disclosure.

In a further aspect, the RFID reading terminal can be incorporated in adata collection system. One embodiment of the data collection system,schematically shown in FIG. 4, can include a plurality of RFID readingterminals 100 a-100 z in communication with a plurality ofinterconnected networks 110 a-110 z.

An RFID reading terminal 100 a-100 z can establish a communicationsession with an external computer 171. In one embodiment, network framescan be exchanged by the RFID reading terminal 100 and the externalcomputer 171 via one or more routers 140, access points 135, and otherinfrastructure elements. In another embodiment, the external computer171 can be reachable by the RFID reading terminal 100 via a local areanetwork (LAN). In a yet another embodiment, the external computer 171can be reachable by the RFID reading terminal 100 via a wide areanetwork (WAN). In a yet another embodiment, the external computer 171can be reachable by the RFID reading terminal 100 directly (e.g., via awired or wireless interface). A skilled artisan would appreciate thefact that other methods of providing interconnectivity between the RFIDreading terminal 100 and the external computer 171 relying upon LANs,WANs, virtual private networks (VPNs), and/or other types of network arewithin the scope of this disclosure.

A “computer” herein shall refer to a programmable device for dataprocessing and control, including a central processing unit (CPU), amemory, and at least one communication interface. For example, in oneembodiment, a computer can be provided by a server running a singleinstance of a multi-tasking operating system. In another embodiment, acomputer can be provided by a virtual server, i.e., an isolated instanceof a guest operating system running within a host operating system. A“network” herein shall refer to a set of hardware and softwarecomponents implementing a plurality of communication channels betweentwo or more computers. A network can be provided, e.g., by a local areanetwork (LAN), or a wide area network (WAN). While different networkscan be designated herein, it is recognized that a single network as seenfrom the application layer interface to the network layer of the OSImodel can comprise a plurality of lower layer networks, i.e., what canbe regarded as a single Internet Protocol (IP) network, can include aplurality of different physical networks.

The communications between the RFID reading terminal 100 and theexternal computer 171 can comprise a series of requests and responsestransmitted over one or more TCP connections. A skilled artisan wouldappreciate the fact that using various transport and application levelprotocols is within the scope and the spirit of the invention.

At least one of the messages transmitted by the RFID reading terminal100 can include decoded message data corresponding to an RFID labelattached to an inventory item. For example, an RFID reading terminal cantransmit a request to the external computer to retrieve productinformation corresponding to a product identifier encoded by an RFID tagattached to a retail item, or to transmit an item tacking record for anitem identified by an RFID tag attached to the item.

As noted herein supra, the RFID reading terminal 100 can be configuredto receive from the external computer 171 an inventory list containingitem identifiers, or count, of items stored within a storage,manufacturing, and/or retail facility. The inventory list or count canfurther contain storage location information of specific items. The RFIDreading terminal 100 can be further configured to reconcile an inventoryof items stored in a manufacturing, retail and/or storage facilityagainst the inventory list or count, by reading RFID tags attached tothe items. The RFID reading terminal 100 can be configured to transmitthe reconciled list or count to the external computer 171.

The RFID reading terminal 100 can be further configured to display ascan trace on the terminal's display, thus providing to the operator avisual feedback with respect to the scanning progress. In oneembodiment, one or more scan traces 111 a, 111 b can be overlaid over animage of physical structure 115 containing the inventory items asschematically shown in FIG. 1. In a further aspect, for a moving RFIDreading terminal, a visual scan trace can be provided by a line definedby a multitude of time varying points, each point being a projection ofthe 3D RF signal coverage shape onto a plane defined by the physicalstructure 115 containing the inventory items at a given moment in time.

A noted herein supra, in one embodiment, the RFID reading terminal cancomprise a two-dimensional imager. The RFID reading terminal can beconfigured to determine a spatial position of the RF signal coverageshape based on the known position and orientation of the RF antennarelatively to the position of the field of view (FOV) of thetwo-dimensional imager, as schematically shown in FIGS. 5 a-5 b.

The plane 2050 can represent an arbitrary chosen plane, e.g., a planeintersecting a physical structure hosting one or more inventory items.The RF antenna can be oriented relatively to the view finder in such away that the central axis 5010 of the field of view of the imager wouldbe parallel to the central axis 5020 of the RF signal coverage shape bythe antenna. Reducing the distance between the RFID reading terminal andthe plane 2050 and/or increasing the RF transmit power level results ina larger projection of the RF signal coverage area onto the plane 5020,as schematically shown in FIGS. 5 a-5 b. In the example of FIG. 5 b, thelesser distance and/or the greater transmit power level results in alarger projection RF signal coverage area onto the plane 5020. Theprojection of the RF signal coverage shape onto the plane 2050 can beentirely within the FOV of the two-dimensional imager, as schematicallyshown in FIG. 5 a, or can be partially outside of the FOV of thetwo-dimensional imager, as schematically shown in FIG. 5 b.

In a further aspect, the RFID reading terminal can be configured tomeasure the distance to an object using a two-dimensional imager. Basedon the known shape of the signal coverage and the distance andorientation of the RF antenna to a physical structure 115 containing theinventory items, the RFID reading terminal can determine and display theprojection of the 3D RF signal coverage shape onto the plane defined bythe physical structure 115.

In another embodiment, the RFID reading terminal can comprise one ormore accelerometers and can be configured to determine the change of thespatial position and orientation of the RF signal coverage shape basedon the proper acceleration values received from the accelerometers. Inone illustrative embodiment, the RFID reading terminal can comprisethree or more accelerometers.

In one embodiment, the RFID reading terminal 100 can be furtherconfigured to display a quantity of scanned items, a quantity of itemswhich have not been scanned yet, and/or a total quantity of items to bescanned, the latter quantity determined based on an inventory count orlist of items describing a storage, manufacturing, and/or retailfacility. A progress indicator 191 of FIG. 1 shows the number of itemsscanned and the total number of items expected to be scanned. In anotherembodiment, the RFID reading terminal 100 can be further configured todisplay a both an absolute progress bar 192 a, and/or a relativeprogress bar 192 b indicating a quantity of scanned items and a totalquantity of items expected to be scanned, as shown in FIG. 6.

In one embodiment, the RFID reading terminal 100 can be furtherconfigured to display an indicator 119 of the RF signal coverage over ascan trace, as schematically shown in FIG. 7. The indicator of the RFsignal coverage can be determined as a line being a projection of the 3DRF signal coverage shape onto a plane defined by the physical structure115 containing the inventory items. In another embodiment, the RFIDreading terminal 100 can be further configured to display an indicator129 of the RF signal coverage over a current position aimed at by theRFID reading terminal, as schematically shown in FIG. 8.

In one embodiment, the RFID reading terminal 100 can be furtherconfigured to display a scan trace overlaid over an image of a physicalstructure (e.g., a shelf) containing one or more scanned items and oneor more items to be scanned. In one embodiment, the image of thephysical structure containing the inventory items can be received by theRFID reading terminal 100 over the network from an external computer. Inanother embodiment, the RFID reading terminal 100 can comprise atwo-dimensional imager, and the image of the physical structurecontaining the inventory items can be acquired by the two-dimensionalimager. In another embodiment, the image of the physical structure isdrawn, with appropriate detail, on the RFID reading terminal display,based on a description of the physical structure received by theterminal 100 via the user interface, from an external peripheral deviceor from an external computer.

In one embodiment, the items which have already been scanned and whichhave not yet been scanned can be displayed in two different colors, asschematically shown in FIG. 9. In another embodiment, the items whichhave already been scanned and which have not yet been scanned can bedisplayed using two different transparency patterns, as schematicallyshown in FIGS. 10-11. In one embodiment, a part of the physicalstructure (e.g., shelves or sections of shelves) containing inventoryitems having not been fully reconciled against the inventory list can beshown using a transparent pattern. In another embodiment, schematicallyshown in FIG. 12, multiple colors and/or transparency pattern can beused to display parts of physical structure containing the inventoryitems which have been fully reconciled, partially reconciled, orcontaining no items having been reconciled. In a yet another embodiment,schematically shown in FIG. 13, quantities of reconciled items can bedisplayed associated with groups of inventory items. Various embodimentsdisplaying scan traces and showing the quantities of inventory items bythe RFID reading terminal 100 are shown in FIGS. 14-19.

In one embodiment, schematically shown in FIG. 20, the RFID readingterminal 100 can be further configured to receive from an externalcomputer and to display a floor plan of the manufacturing, retail and/orstorage facility. The RFID reading terminal can be further configured todisplay its position on the floor plan. The RFID reading terminal can befurther configured to display in two or more different colors one ormore areas containing the items which have already been scanned and oneor more areas containing the items which have not yet been scanned.

In a further aspect, RFID reading device 333 can be compliant with EPC™Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz-960MHz by EPCglobal, commonly known as the “Gen 2” standard, which definesphysical and logical requirements for a passive-backscatter,interrogator-talks-first (ITF) RFID system operating in the 860 MHz-960MHz frequency range.

In one embodiment, RFID reading terminal 100 can transmit information toa passive RFID tag by modulating an RF signal in the 860-960 MHzfrequency range. An RFID tag can receive both information and operatingenergy from the RF signal transmitted by the RFID reading terminal 100.RFID reading terminal 100 can receive information from the RFID tag bytransmitting a continuous-wave (CW) RF signal to the RFID tag.“Continuous wave” can refer to any waveform transmitted by an RFIDreading device and suitable to power a passive RFID tag, e.g., asinusoid at a given frequency. The RFID tag can respond by modulatingthe reflection coefficient of its antenna, thus backscattering aninformation signal to the RFID reading terminal 100. In one embodiment,the RFID tag can modulate the reflection coefficient of its antenna onlyresponsive to receiving an RFID signal from RFID reading terminal 100.

In a further aspect, RFID reading terminal 100 can be configured to sendinformation to one or more RFID tags by modulating an RF carrier usingdouble-sideband amplitude shift keying (DSB-ASK), single-sidebandamplitude shift keying (DSB-ASK), or phase-reversal amplitudeshift-keying (PR-ASK) using a pulse-interval encoding (PIE) format. RFIDtags can receive their operating energy from the same modulated RFcarrier.

The RFID reading terminal 100 can be configured to receive informationfrom an RFID tag by transmitting an unmodulated RF carrier and listeningfor a backscatter reply. RFID tags can transmit information bybackscatter-modulating the amplitude and/or phase of the RFID carrier.RFID tags can encode the backscattered data using, e.g., FM0 baseband orMiller modulation of a subcarrier at the data rate. The encoding methodto be employed by an RFID tag can be selected by the RFID readingterminal 100.

In another aspect, RFID reading terminal can establish one or moresessions with one or more RFID tags. An RFID tag can support at leastone session-dependent flag for every session. The session-dependent flagcan have two states. An RFID tag can invert a session-dependent flagresponsive to receiving a command from RFID reading terminal 100. Tagresources other than session-dependent flags can be shared amongsessions. In another aspect, an RFID tag can support a selected statusflag indicating that the tag was selected by the RFID reading terminal100.

Responsive to receiving an interrogation signal transmitted by the RFIDreading terminal 100, an RFID tag can transmit a response signal back toRFID reading terminal 100. The response signal can contain useful data,e.g., an Electronic Product Code (EPC) identifier, or a tag identifier(TID). The response signal can include a representation of a binarystring, at least part of which is equal to at least part one of thespecified one or more target item identifiers.

In one embodiment, RFID reading terminal can implement EPC™ Class-1Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHz byEPCglobal. The RFID reading terminal 100 can interrogate RFID tags usingthe commands described herein infra.

Select command can be used by the RFID reading terminal 100 to select aparticular RFID tag population for the subsequent inventory round.Select command can be applied successively to select a particular tagpopulation based on user-specified criteria. Select command can includethe following parameters:

Target parameter indicates whether Select command modifies a tag's SLflag or Inventoried flag, and in the latter case it further specifiesone of four available sessions (S0, . . . , S3);

Action parameter indicates whether matching tags assert or deassert SLflag, or set their Inventoried flag to A or B state; tags conforming tothe contents of MemBank, Pointer, Length, and Mask parameters areconsidered to be matching;

Mask parameter contains a bit string that a tag should compare to amemory location specified by MemBank, Pointer, and Length parameters;

MemBank parameter specifies the memory bank to which Mask parameterrefers (EPC, TID, or User);

Pointer parameter specifies a memory start location for Mask;

Length parameter specifies the number of bits of memory for Mask; ifLength is equal to zero, all tags are considered matching.

Inventory command set can be used by the RFID reading terminal 100 tosingle out one or more individual tags from a group. A tag can maintainup to four simultaneous sessions and a binary Inventoried flag for eachsession. Inventory command set includes the following commands:

Query command can be used to initiate and specify an inventory round; itcontains a slot counter value (Q=0 to 15) determining the number ofslots in the round; the command also includes Sel parameter specifyingwhich tags should respond to the Query.

QueryAdjust command can be used to adjust the value of the tag's slotcounter Q without changing any other parameters;

QueryRep command can be used to repeat the last Query command;

Ack command can be used to acknowledge a tag's response;

NAK command can be used to force a tag to change its state to Arbitrate.

An RFID tag can implement a state machine. Once energized, a tag canchange its current state to Ready. A selected tag can, responsive toreceiving Query command, select a random integer from the range of [0;2^(Q-1)]. If the value of zero is selected, the tag can transition toReply state, backscattering a 16-bit random number. If a non-zero valueis selected, the tag can load the selected random integer into its slotcounter and change its state to Arbitrate.

Responsive to receiving the tag transmission, RFID reading terminal canacknowledge it with Ack command containing the same random number.Responsive to receiving Ack command, the tag can change its state toAcknowledged and backscatter its protocol control (PC) bits, EPC andcyclic redundancy check (CRC) value. Unacknowledged tag can select a newrandom integer from the range of [0; 2^(Q-1)], load the value into itsslot counter, and change its state to Arbitrate. Responsive to receivingQueryAdjust command, a tag in the Arbitrate state should decrement thevalue of its slot counter and backscatter its protocol control (PC)bits, EPC and CRC value if its slot counter is equal to zero.

Responsive to receiving the tag's transmission of its PC, EPC and 16-bitCRC value, RFID reading terminal can send a QueryAdjust command causingthe tag to invert its Inventoried flag and to transition to Ready state.

Access command set can be used by the RFID reading terminal 100 forcommunicating with (reading from and writing to) a tag. An individualtag must be uniquely identified prior to access. Access command setincludes the following commands:

ReqRn command can be used by the RFID reading terminal 100 to request ahandle from a tag; the handle can be used in the subsequent Accesscommand set commands. Responsive to receiving Req_RN commands, a tagreturns a 16-bit random integer (handle) and transitions fromAcknowledged to Open or Secured state.

Read command can be used by the RFID reading terminal 100 to read tag'sReserved, EPC, TID and User memory;

Write command can be used by the RFID reading terminal 100 to write totag's Reserved, EPC, TID and User memory;

Kill command can be used by the RFID reading terminal 100 to permanentlydisable a tag;

Lock command can be used by the RFID reading terminal 100 to lockpasswords preventing subsequent read or write operations; lockindividual memory banks preventing subsequent write operations;permanently lock the lock status of passwords or memory banks;

Access command can be used by the RFID reading terminal 100 to cause atag having a non-zero access password to transition from Open to Securedstate.

A skilled artisan would appreciate the fact that other methods ofinterrogating RFID tags by the RFID reading terminal 100 are within thescope of this disclosure.

One embodiment of the RFID reading terminal 100 is schematically shownin FIGS. 21 a (front panel view), 21 b (side panel view), and 21 c(bottom panel view). The RFID reading terminal 100 can comprise ahousing 52 within which other components of the RFID reading terminal100 can be disposed. An LCD screen display with a touch screen sensor554 can be disposed on the front panel 556. Also disposed on the frontpanel 556 can be a decode LED 558, a scan LED 559, and a keyboard 64including a scan key 568 and navigation keys 72. An imaging window 74can be disposed on the top panel of housing 52. Disposed on the sidepanel (best viewed in FIG. 21 b) can be an infra-red communication port76, an access door to a secure digital (SD) memory interface 78, anaudio jack 80, and a hand strap 82. Disposed on the bottom panel (bestviewed in FIG. 22 c) can be a multi-pin mechanical connector 84 and ahand strap clip 86. RFID reading device (not shown in FIGS. 21 a-21 c)can be disposed within the housing 52.

While the present invention has been particularly shown and describedwith reference to certain exemplary embodiments, it will be understoodby one skilled in the art that various changes in detail may be affectedtherein without departing from the spirit and scope of the invention asdefined by claims that can be supported by the written description anddrawings. Further, where exemplary embodiments are described withreference to a certain number of elements it will be understood that theexemplary embodiments can be practiced utilizing less than the certainnumber of elements.

A small sample of systems, methods, and apparata that are describedherein is as follows:

A1. A portable radio-frequency identifier (RFID) reading terminalcomprising:

a microprocessor;

a memory;

an RFID reading device comprising a radio frequency (RF) antenna;

a display;

wherein said portable RFID reading terminal is configured to display ascan trace; and

wherein said scan trace is provided by a line comprising a plurality oftime varying points, each point being defined by a projection of acoverage shape of an RF signal transmitted by said RFID reading deviceonto a chosen plane at a given moment in time.

A2. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is configured, by reading RFID tags attached tosaid items, to reconcile an inventory of items stored in a facilityagainst at least one of: an expected inventory list, an expected countof items.

A3. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is configured , by reading RFID tags attached tosaid items, to reconcile an inventory of items stored in a facilityagainst at least one of: an expected inventory list, an expected countof items; and

wherein said RFID terminal is configured to receive from an externalcomputer at least one of: said expected inventory list, said expectedcount of items.

A4. The portable RFID reading terminal of (A1), further comprising auser interface;

herein said portable RFID reading terminal is configured, by readingRFID tags attached to said items, to reconcile an inventory of itemsstored in a facility against at least one of: an expected inventorylist, an expected count of items; and

wherein said RFID terminal is configured to receive via said userinterface at least one of: said expected inventory list, said expectedcount of items.

A5. The portable RFID reading terminal of (A1), further comprising atwo-dimensional imager;

wherein said portable RFID reading terminal is configured, by readingRFID tags attached to said items, to reconcile an inventory of itemsstored in a facility against at least one of: an expected inventorylist, an expected count of items; and

wherein said RFID terminal is configured to receive via saidtwo-dimensional imager at least one of: said expected inventory list,said expected count of items.

A6. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is configured, by reading RFID tags attached tosaid items, to reconcile an inventory of items stored in a facilityagainst at least one of: an expected inventory list, an expected countof items; and

wherein said RFID terminal is configured to receive from an externalmemory device at least one of: said expected inventory list, saidexpected count of items.

A7. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is configured, by reading RFID tags attached tosaid items, to reconcile an inventory of items stored in a facilityagainst at least one of: an expected inventory list, an expected countof items; and

wherein said RFID terminal is configured to receive from a firstexternal computer at least one of: said expected inventory list, saidexpected count of items; and

wherein said RFID terminal is further configured to transmit to a secondexternal computer at least one of: a list of read RFID tags, a count ofread RFID tags.

A8. The portable RFID reading terminal of (A1), further comprising atwo-dimensional imager;

wherein said portable RFID reading terminal is further configured todetermine a spatial position of said RF signal coverage shape based on aknown position and orientation of said RF antenna relatively to aposition of a field of view of said two-dimensional imager.

A9. The portable RFID reading terminal of (A1), further comprising atwo-dimensional imager;

wherein said portable RFID reading terminal is further configured tomeasure a distance to an object using said two-dimensional imager; and

wherein said portable RFID reading terminal is further configured todetermine and display a projection of said RF signal coverage shape ontothe plane defined by a physical structure.

A10. The portable RFID reading terminal of (A1), further comprising atleast one accelerometer;

wherein said portable RFID reading terminal is further configured todetermine a change of a spatial position and orientation of said RFsignal coverage shape based on proper acceleration values received fromsaid at least one accelerometer.

A11. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to display at least one of:a quantity of scanned items, a quantity of items which have not bescanned yet, a total quantity of items to be scanned.

A12. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to display an indicator of aratio of quantity of scanned items to a total quantity of items to bescanned.

A13. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to display said scan traceoverlaid over an image of a physical structure.

A14. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to receive an image of aphysical structure; and

wherein said portable RFID reading terminal is further configured todisplay said scan trace overlaid over said image of said physicalstructure.

A15. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to receive a description ofa physical structure;

wherein said portable RFID reading terminal is further configured tocreate an image of said physical structure based on said description;and

wherein said portable RFID reading terminal is further configured todisplay said scan trace overlaid over said image of said physicalstructure.

A16. The portable RFID reading terminal of (A1), further comprising atwo-dimensional imager;

wherein said portable RFID reading terminal is further configured, usingsaid two-dimensional imager, to acquire an image of a physicalstructure; and

wherein said portable RFID reading terminal is further configured todisplay said scan trace overlaid over said image of said physicalstructure.

A17. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to display an indicator ofan RF signal coverage over said scan trace overlaid over an image of aphysical structure.

A18. The portable RFID reading terminal of (A1), wherein said portableRFID reading terminal is further configured to display a indicator of anRF signal coverage over a current position within said scan trace.

The invention claimed is:
 1. A radio-frequency identifier (RFID) readercomprising: a radio frequency (RF) antenna that outputs an RF signal;wherein a scan trace is displayed in response to outputting the RFsignal and the scan trace comprises a plurality of time-varying points,each point being defined by a projection of the RF signal transmitted bythe RFID antenna onto a plane at a given moment in time.
 2. The RFIDreader of claim 1, wherein, by reading RFID tags attached to items, aninventory of items stored in a facility are reconciled against at leastone of: an expected inventory list and an expected count of items. 3.The RFID reader of claim 2, wherein the RFID reader is configured toreceive from an external computer at least one of: the expectedinventory list and the expected count of items.
 4. The RFID reader ofclaim 3, further comprising a user interface; wherein at least one ofthe expected inventory list and the expected count of items is receivedvia the user interface.
 5. The RFID reader of claim 3, furthercomprising a two-dimensional imager; wherein at least one of theexpected inventory list and the expected count of items is received viathe two-dimensional imager.
 6. The RFID reader of claim 2, wherein atleast one of: (1) the expected inventory list and (2) the expected countof items, is received from an external memory device.
 7. The RFID readerof claim 3, wherein at least one of: a list of read RFID tags and acount of read RFID tags is transmitted to a second external computer. 8.The RFID reader of claim 1, further comprising a display that displaysthe scan trace.
 9. The RFID reader of claim 1, further comprising atwo-dimensional imager; wherein each point is defined by a projection ofa coverage shape of an RF signal transmitted by the RFID antenna ontothe plane at a given moment in time, and wherein a spatial position ofthe coverage shape of the RF signal is determined based on a knownposition and orientation of the RF antenna relatively to a position of afield of view of the two-dimensional imager.
 10. The RFID reader ofclaim 1, further comprising a two-dimensional imager; wherein each pointis defined by a projection of a coverage shape of an RF signaltransmitted by the RFID antenna onto the plane at a given moment intime, wherein a distance to an object is measured using thetwo-dimensional imager; and wherein a projection of the RF signalcoverage shape determined and displayed onto the plane defined by aphysical structure.
 11. The RFID reader of claim 1, further comprisingat least one accelerometer; wherein each point is defined by aprojection of a coverage shape of an RF signal transmitted by the RFIDantenna onto the plane at a given moment in time, and wherein a changeof a spatial position and orientation of the RF signal coverage shape isdetermined based on proper acceleration values received from the atleast one accelerometer.
 12. The RFID reader of claim 1, wherein atleast one of the following is displayed: a quantity of scanned items, aquantity of items which have not be scanned yet, and a total quantity ofitems to be scanned.
 13. The RFID reader of claim 1, wherein anindicator of a ratio of quantity of scanned items to a total quantity ofitems to be scanned is displayed.
 14. The RFID reader of claim 1,wherein the scan trace is displayed overlaid over an image of a physicalstructure.
 15. The RFID reader of claim 14, wherein the image of thephysical structure is received.
 16. The RFID reader of claim 1, whereina description of a physical structure is received; wherein an image ofthe physical structure is created based on the description; and whereinthe scan trace is displayed overlaid over the image of the physicalstructure.
 17. The RFID reader of claim 1, further comprising atwo-dimensional imager; wherein, using the two-dimensional imager, animage of a physical structure is acquired; and wherein the scan trace isdisplayed overlaid over the image of the physical structure.
 18. TheRFID reader of claim 1, wherein an indicator of an RF signal coverage isdisplayed over the scan trace overlaid over an image of a physicalstructure.
 19. The RFID reader of claim 1, wherein an indicator of an RFsignal coverage is displayed over a current position within the scantrace.
 20. A method comprising: outputting an RF signal from anradio-frequency identifier (RFID) reader; displaying a scan trace inresponse to the outputting the RF signal, wherein the scan tracecomprises a plurality of time-varying points that are each defined by aprojection of the RF signal transmitted by the RFID antenna onto a planeat a given moment in time.